Loess-derived sediments represent the most widespread soil parent materials in the Pannonian region of Croatia. Pseudogley, as the most common soil type in this region, developed mainly on such ...parent materials. Pseudogleys largely correlate with the WRB Reference Soil Group of Stagnosols. On the General Soil Map of Croatia at scale 1: 50 000 (GSM of Croatia), the distinction is made between Pleistocene loams (PL) and loess as Pseudogley parent materials. The initial purpose of this research was to investigate if the criteria for this distinction were clear and consistent and if the terms used for labeling these parent materials were adequate. Hence, we investigated parent materials of 18 Pseudogleys across 6 different locations (three on loess and three on PL) in the Pannonian region of Croatia. We analyzed their morphology (including micromorphology of three representative parent materials), particle size distribution, total porosity, pH, and mineral assemblages (by modal analysis of three representative parent materials). Following these analyses, no systematic differences between the loess parent materials and the PL parent materials were found. Additionally, it was concluded that, due to significant geogenetic and/or pedogenetic alterations of all studied parent materials, none of them should be labeled simply as loess. Hence, parent material at one location was labeled as leached loess derivate, and parent materials at all other locations were labeled as pseudogleyed loess derivates. Both types of parent materials were described in detail and defined. In addition, the terminology and the classification of loess(-derived) parent materials in general was proposed. The analyzed pseudogleyed loess derivates were not completely uniform across the investigated locations. Primarily, this was due to the polygenesis of loess (reflected by differences in particle size distributions and compositions of light and heavy mineral fractions). Secondarily, it was due to the 600–1100 mm MAP gradient along the study region (reflected by differences in pH values and properties of redoximorphic features). Although pedogenesis of the investigated parent materials might have started already during the Late Glacial and have continued throughout the Holocene at varying (and overall decreasing) rates, their morphology indicates that pseudogleization and lessivage are still active processes, which occur simultaneously in the analyzed parent materials and agree with the present climate.
Clay mineralogy of Plio-Quaternary sediments of SE slopes of Medvednica Mt. was compared to that of the overlying weathering horizons. Three locations of Plio-Quaternary sediments, representing past ...weathering products, were sampled along with the overlying material, representing more recent weathering cycles. Particle size distribution, pH and cation exchange capacity (CEC) of the samples were analyzed. Bulk mineralogy was determined using X-ray diffraction (XRD). Clay mineralogy was determined, after carbonate cement, organic matter and free Fe oxides removal, on fractions < 2 and < 0.2 μm using XRD and Fourier-transform infrared spectroscopy (FTIR). Average layer charge of the expandable layers was determined using the O-D method. Major elements content was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Bulk mineralogy comprises quartz, feldspars, mica, clay minerals and occasional Al and Fe (oxy)hydroxides. Clay mineralogy differs subtly between samples; dioctahedral expandable clay minerals dominate with illite and kaolinite present. Hydroxyl interlayering of expandables is noted in the surface samples, corresponding to lower CEC values. Average absolute layer charge of the expandable layers is higher in the surface samples and decreases with depth on two of the investigated locations. Overall, clay mineralogy of the Plio-Quaternary sediments reflects a more intensive weathering regime, confirmed by the presence of Al (oxy)hydroxides and lower absolute charge of the expandable layers. The weathered material and soil overlying these sediments shows heterogeneity in genesis, but corresponds to less intense weathering regime, confirmed by the formation of hydroxy-interlayered minerals and higher absolute charge of the expandable layers.
Hillslope hydrology in agricultural landscapes is complex due to a variety of hydropedological processes and field management possibilities. The aim was to test if there are any differences in soil ...properties and water regime along the hillslope and to compare vineyard rows (vine) with inter-rows (grass) area for those properties. The study determined that there are significant differences in the contents of soil particle fractions, pH, and humus content along the slope (
< 0.0001), with lower confidence level in bulk density
< 0.05). Differences between row and inter-row space were significant for the pH, humus, and silt content, but for sand and clay content, and bulk density differences were not determined. The study determined differences in soil water content among five slope positions (
< 0.0001), and between row and inter-row vineyard space (all with
< 0.05). Where in the upper slope positions (e. g., P1) soil water content was higher than on lower slope positions. Higher soil water content was observed at higher slope positions, associated with clay content. However, it can be concluded that the retention of moisture on the slope is more influenced by local-scale soil properties (primarily soil texture) and variability of the crop (row/inter-row) than the position on the slope.
•Clay minerals in soils formed from marls in temperate climate were studied.•High pH hampers pronounced clay minerals transformation.•Clay minerals in soils are mainly inherited from parent ...material.•Slight changes detected in mixed-layered clay minerals and interlayer space.
Five young soil profiles, formed from Miocene marls and argillaceous limestone, were investigated to determine changes in their clay mineralogy. Soil profiles were described, sampled, and their basic properties analyzed (particle size distribution, pH, cation exchange capacity (CEC), CaCO3 and organic C contents). The soils were classified according to the WRB classification as: 1) Calcaric Mollic Leptosol (Humic); 2) Calcaric Lithic Leptosol (Humic); 3) Calcaric Regosol (Loamic, Relocatic); 4) Calcaric Regosol (Siltic); and 5) Calcaric Cambisol (Densic, Endoloamic, Episiltic). Mineralogy was determined via X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) on bulk samples and clay fractions, and chemical composition was determined by inductively coupled plasma emission spectroscopy (ICP-ES). Calcite, quartz and some plagioclase alongside phyllosilicates were identified in parent material. Dolomite was found in the parent material of younger age. Clay fraction from parent material consists of expandable clays (smectite-rich illite-smectite and vermiculite), illite and kaolinite, with chlorite present in younger parent materials. In most soil horizons dissolution and leaching of less stable phases (calcite, dolomite, chlorite) occurred. Initial stage soil formation is consistent with the dominant influence of parent rock mineralogy on soil clay mineral assemblage. Analyses showed substantial homogeneity between and within profiles; nevertheless, slight changes in the clay mineralogy were noted: decrease of illite layers in illite-smectite in topsoil samples and occurrence of mixed-layered chlorite-vermiculite and/or hydroxyl or organic matter interlayering in soil horizons. Chemical composition of bulk samples indicated mobility only of alkali elements, confirming weak chemical weathering. The results show slight changes in clay mineralogy, which can be detected in young soils developed from calcareous parent material under high pH conditions. Those weak alterations of parent clay minerals assemblage, often through unstable phases, can modify soil properties, but are also indicators of subtle clay transformation in calcareous soils in temperate climate.
A polygenetic soil formed on Late Glacial Loess on the Island of Susak was investigated by means of high-resolution depth approach to give pedosedimentary and palaeoenvironmental reconstructions of ...the Late Glacial/Holocene pedosequence. The complete polygenetic profile (A-2C1-2C2-3Btb-4Ck), defined as Eutric Leptic Regosol (Geoabruptic, Siltic, Ruptic) over Argic horizon over loess deposit, is a result of the interaction of the sediments (loess) with environmental conditions from the Late Glacial throughout the Holocene. Both normal pedogenesis and erosion/sedimentation-driven pedogenesis influenced its development. Therefore, this profile bears valuable imprints of climate, vegetation, land surface, and land use changes in this part of the Adriatic area for the time period covering the past 16 ka. The 4Ck horizon is a remnant of an A-C soil profile, whose incipient formation corresponds to a steppe-like palaeo-vegetation and a semi-humid to semi-arid palaeo-climate. The 3Btb horizon has blocky structure; common clay coatings and infillings that are related to the walls of channel macrovoids; increased CIA, Al/Si and Ba/Sr ratios due to the increase of the Al and clay contents; highest Fet, Fed, Mnt and Mnd values due to abundant redox concentrations; and specific clay mineralogy. Since the obtained age of the loess deposit (4Ck horizon) underlying the 3Btb horizon is 16.1 ± 1.3 ka (can be correlated to the Late Glacial Maximum, i.e., OIS-2), we find that the period of the Bølling-Allerød warming might have enabled the formation of the highly weathered 3Btb horizon within a Luvisol-like soil. After the period of surface stability, a period of forest decay and surface instability took place, resulting with the erosion of the Luvisol. The 3Btb horizon was then covered with a homogeneous loess material (whose deposition can presumably be related to the Younger Dryas period), inside of which the horizons 2C1 and 2C2 are recognized. Both these horizons are negligibly affected by pedogenesis and contain artefacts. The incipient soil formation in the upper part of the profile, along with the irregular lower boundary of the A horizon and the lithic discontinuity between the A horizon and the 2C1 horizon, points to the possibility of a very recent and minor aeolian deposition. However, one should not overlook the potential impacts of human activities and/or colluvial depositions on the properties of the A, 2C1, and 2C2 horizons.
•Relict tropical soil properties preserved in present-day humid subtropical climate.•Multiple evidence of polygenesis in a 3-meters-deep terra rossa soil profile.•Clay distribution along the soil ...profile clearly indicates lithic discontinuities.•Ferralitization and lessivage processes diagnosed throughout the terra rossa profile.•Fine clay dominated by authigenic kaolinite nanoparticles.
Terra rossa soils on the Istrian peninsula are generally considered polygenetic relict soils. They overlie and mark the youngest subaerial unconformity in the northwestern part of the Adriatic Carbonate Platform and are susceptible to erosional and redepositional processes. Terra rossa soils represent a valuable archive of information that can be used to understand present and past soil formation processes in the context of climate variability and landscape dynamics, especially in low-lying parts of the karst landscape where thicker deposits are typically found. We studied a 3 m thick terra rossa profile in a karst depression on the northernmost part of the southwestern Istrian planation surface and analysed the micromorphology, physical/chemical properties, geochemistry, bulk and clay mineralogy, and composition of heavy and light mineral fractions. The profile shows several signs of colluviation and polygenesis with clay distribution along the profile, clearly indicating lithic discontinuities. Kaolinisation, along with iron oxide formation, is the dominant process in the studied profile. Ferralitisation and lessivage processes were diagnosed throughout the profile, with intense clay translocation occurring despite the extremely stable soil microaggregates. In accordance with the WRB system, the profile is classified as Rhodic Lixisol (Clayic, Aric, Cutanic). This implies that some terra rossa soils, previously classified as e.g. Cambisols or Luvisols, might actually be Lixisols or other (sub-)tropical soils (e.g. Nitisols), in which relict properties are preserved in the present climate. The finding of a Lixisol in the study area indicates the old age of the surface of the karst depression and provides the first data on the burial history of the southwestern Istrian planation surface. We suggest the older Quaternary interglacials, the mid-Piacenzian Warm Period (Pliocene) and the Miocene Climatic Optimum as favourable periods for the formation of the studied soil.
Three Pseudogley profiles – Stagnic Cutanic Albeluvisol (Dystric, Siltic), Stagnic Cutanic Albeluvisol (Eutric, Siltic) and Luvic Stagnosol (Hypereutric, Siltic) – were studied along the 700–1000mm ...mean annual precipitation (MAP) gradient in the Pannonian region of Croatia. The aim was to compare their composition and properties and to determine the major processes of their formation, as well as to show whether investigations of Pseudogley climosequences in this part of Pannonian Basin are feasible. All three soil profiles were formed in situ from initially vertically homogeneous, previously cycled and post-depositionally modified loess deposits of same provenance (given their morphology, texture, geochemical ratios and mineralogy). Substantial morphological and physical (A horizons colors; Eg horizons thicknesses, colors, bulk densities and porosities; Btg horizons redoximorphic features) as well as chemical soil properties (pH, base saturation, topsoil organic C content) corresponded to the precipitation gradient. On the other hand, due to slight differences between their parent materials, clay content and CEC values of the investigated profiles did not increase with the increase of MAP. Nevertheless, processes of acidification and pseudogleying were found to be least pronounced at the location with the lowest MAP, and most pronounced at the location with the highest MAP. Intensity of lessivage, as one of major pedogenetic processes in all three investigated Pseudogleys, did not correspond to the precipitation gradient, since it was more a function of soil pH and clay mineralogy, than MAP. The three pedogenetic processes were recognized on the basis of obtained pH, base saturation, CIA (Chemical Index of Alteration) and Ti/Al values, as well as soil texture, morphology (presence and characteristics of clay coatings and redoximorphic features) and phyllosilicate dynamics (comminution of chlorite into the clay fraction, vermiculitization, smectite translocation) observed along the investigated profiles. Given the uneven environmental conditions of loess depositions across the Pannonian region of Croatia and the resulting incomplete uniformity of loess parent materials, investigations of Pseudogley climosequences in this part of the Pannonian Basin should be approached with caution.
•Substantial Pseudogley features correspond to precipitation gradient.•Lessivage is the main process in creation of the vertical texture contrast.•Lessivage is a function of soil pH and clay mineralogy, rather than precipitation.•Chlorite, illitic material and kaolinite are inherited from parent material.•C–V MLM and vermiculite are formed as a result of chlorite destabilization.
Pseudogley is a soil characterized by vertical texture contrast and periodic stagnation of precipitation water. Its profile is often designated as A-Eg-Btg-Cg. It is the second most frequent soil ...type in Croatia, found almost exclusively on non-calcareous loess sediments in the Pannonian region of the country. The aim of this research was to determine if differences in particle size distribution and basic chemical properties exist among Pseudogleys formed along the 600–1100mm mean annual precipitation (MAP) gradient on two different relief positions (plateau and slope) across the Pannonian region of Croatia. A total of 33 soil pits were dug in natural forests. The trends observed with soil depth for particle size distribution, organic C content, pH, Ca2+/Mg2+ ratio, and base saturation point to the predominance of top-down formation of the investigated soil profiles. Both relief and climate influenced the distribution of Pseudogleys across the Pannonian region of Croatia. The incomplete homogeneity of loess parent materials across the study region governs the variations in clay content, silt content, and cation exchange capacity among the investigated Pseudogleys. Conversely, the increase in MAP along the investigated transect caused a decrease in soil pH, base saturation, and Ca2+/Mg2+ ratio, and the increase in organic C content along the investigated profiles. Therefore, future studies of climate impact on loess-derived soils in this region should take into account only soil chemical properties that are not directly dependent on particle size distribution. The relief position on which soil pits were situated had no effect on soil characteristics. Hence, it seems that Pseudogleys should not be systemized according to their position on plateau or on slope, as it is the case in some classification systems.
•Loess parent materials across the studied region are only partly homogeneous.•Climate and relief are key factors of Pseudogley distribution in the studied region.•Climate influenced pH, base saturation and C content of the analyzed soil profiles.•Relief position had a negligible impact on the analyzed soil characteristics.
Stagnosols are the most widespread soils in the Pannonian region of Croatia. In Croatia they are referred to as Pseudogleys and considered to form primarily by normal (top–down) pedogenesis. However, ...the formation of their non-calcareous loess parent materials probably involved different sources, transports, and depositional environments. We aimed to determine the courses of soil formation and the characteristics of three Stagnosol profiles studied along the mean annual precipitation (MAP) gradient (700–1100mm) in the Pannonian region of Croatia. We found that soil redoximorphic features formed in situ by ongoing pseudogleization. Vertical trends for the clay/silt and coarse/fine silt ratios pointed to top–down pedogenesis. However, high organic C content at the bottom of one soil profile is the result of erosion/sedimentation processes, whereas high clay content in the subsoil of another profile was largely the result of sedimentation in a shallow paleo-lake. Therefore, some Croatian Stagnosols should be considered polygenetic. Each soil profile was classified using the WRB system, and the new WRB-2014 version proved more suitable than the previous one (WRB-2006). However, suggestions for improvements are given. In line with the MAP gradient were several morphological and only two chemical (pH and base saturation) soil characteristics. Organic C content did not correspond to MAP due to variability of forest topsoils. Clay content and CEC did not agree with MAP due to variability of loess parent materials across the Pannonian region of Croatia. The existence of more than one source of loess material (confirmed by the modal analysis) and the differences in depositional paleo-environments resulted in slightly different mechanical compositions of the investigated parent materials. We concluded that both climate and parent material must be regarded as key factors for the formation and characteristics of Stagnosols in the Pannonian region of Croatia (and the wider southwestern Pannonian Basin).
•Most Croatian Stagnosols formed by top–down pedogenesis, but some are polygenetic.•Argic horizon may have as much as 1.2 times more clay than the overlying horizon.•Soil pH and base saturation were affected by precipitation gradient in the region.•Soil clay content and CEC were affected by parent material heterogeneity.•Soil mechanical and mineral compositions indicate more than one source of loess.
Red palaeosol (RP) covering the carbonate basement exposed at the bottom of the loess section and lithified terra rossa-like materials situated in cavities (LTR1) and karstified fissures (LTR2) in ...Cretaceous limestones were investigated by means of high-resolution approach, to give a systematic and deeper palaeopedological insight into reddish materials and the exposed red palaeosols on the island of Susak. Both, selected geochemical indicators of weathering (Al/Si, (Na + K)/Al and Fed/Fet) and provenance (La/Ce), as well as detailed mineralogical analysis clearly showed differences among LTR1, LTR2 and RP, respectively. LTR1 and LTR2 represent erosional remains of different soils that existed on the surface of the limestone bedrock prior to the formation of the RP. LTR2 has the highest ZTR (zircon-tourmaline-rutile index) index and contains bauxite minerals (gibbsite and boehmite), clays (kaolinite and mixed-layer clay minerals), and haematite. LTR2 bears characteristics of reworked bauxitic materials mixed with other soils that existed on the surface of the carbonate basement. Those materials might have been mixed and transported until they were captured in the karstified fissure, and, subsequently interlocked with calcite veins and lithified. This might have happened from the Eocene age on. Our attempt to resolve the age of LTR2 formation more precisely, using palaeomagnetic investigations, did not give unambiguous results because the extremely viscous behaviour of the LTR2 samples hinders the acquisition of a stable remanent magnetisation. If we exclude the secondary calcite, LTR1 bears typical mineralogical and geochemical characteristics (e.g. Fed/Fet ratio) similar to those of Istrian terra rossa. Insoluble residues of Cretaceous limestone might have been the main parent materials for the LTR1 formation while the most likely additional fluxes influencing terra rossa formation on the island of Susak were aeolian dust and flysch. The erosion remains ended in limestone cavities and were mixed with cm to dm sized angular and subangular limestone clasts and, subsequently, interlocked with calcite veins and lithified. The investigated RP profile comprised the following mineral horizons: Bwb1-Bwb2-Bwb3-R. The RP formed in a lithologically uniform material that dominantly presents a mixture of loess and, partly, remains of older soils (e.g. rounded clay coatings not related to macrovoids) that existed on the surface of the Cretaceous limestone. Fed/Fet ratio in RP reflects a low degree of weathering of Fe-containing primary silicates. Therefore, we can conclude that the RP does not fit a rather limited variation of selected Fe-oxide characteristics typical for terra rossa. The investigated RP was classified independently of the overlying material. The full name of the palaeosol that we classified is as follows: Hypereutric Chromic Cambisol (Episiltic, Endoloamic). Since no reversal of the EMF was recorded in the RP, we concluded that the RP formed during the Brunhes epoch. Luminescence dating was applied to establish the age of the RP. Based on the acquired data, we assume that the RP very likely formed during the Penultimate Interglacial (OIS7).
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